Spall kiln and process of burning lime therein



Dec. '14 1926.

' w. WARD SP-ALL KILN AND PROCESS OF BURNINGLIME THEREIN Filgd Sept. 11, 1925 2 Sheets-Sheet 1 Dec. 14 1926.

W. WARD SPALL KILN AND PROCESS OF BURNING LIME THEREIN 2 Sheets-Sheet 2 Filed Sept. 11. 1925 ammo c Mlarl Mm Patented cc. 14, 1926.

1 sTAE winnunr whine, or s'rn. GENEVIEVE, Mrssounr.

v SPALL KILN AND PROCESS OF BURNING LIME THEREIN.

Application filed September The invention relates to lime kilns, and

has as an object the provision ofa lime kiln provided with meansto burn large lumps of lime stone in the usual manner, and in addition thereto to burn small lumps of lime stone known in the trade as spalls.

It is a further object of the invention to provide a lime kiln which will burn spalls "without direct contact of the stone or the resultant lime with products of combustion,

whereby an especially pure form of lime may be secured. a r

I It is a further object of the invention to provide a lime kiln having means to burn is spalls by application of heat which is' ordi narily wasted. J z

It is a further object of the invention to provide 'an improved process of burning lime utilizing heretofore wasted spalls and ipiroducin-g therefrom a, superior grade of Further objects of the invention will appear from the following description when read in connection with the accompanying drawings, in which- Fig. 1 is a central vertical section, and Figs.- 2 and 3 are horizontal sections on lines 2, 2, and 3, 3 respectively.

As shown, the device comprises a central shaft 10 having a plurality of furnaces 11,

12, 13,14, to provide heat for the burning of lime stone placed 'in the central shaft to the -form of lime.

As shown, each of the furnaces is provided with a grate 15, and a furnace arch 16, the arch being provided with means for heating air of combustion, in the form of channels 17.

Means for admission of fuel to the grate passages. The products of combustion from the furnaces is allowed to pass to" the central stack 10, and to travel upwardly therein through the mass of broken lime stone, thereby to burn the lime stone to the form of quick lime in the well known manner.

To discharge the burned lime from the stack- 1(),there are shown openings 19 which are provided with any. desirable form of closure 20, so that acart may bedriven 'into -either .of the passages 21, '22, and a closure 20 may be opened to allow the'lime to'be drawn off into the cart.

To deflect the burned lime to the o enings a. spreader is shown in the form 0 "inter- 15 is shown at 18 in the form ofvertical' '11, 1925. Serial No. 55,714.

secting wedgeshaped portions 23 to deliver the lime by gravity to the openings 19.

It is ordinarily impossible to burn the spalls with the large sized limestone for the reason that the presence of the small pieces in the kiln would stop up the interstices between the large pieces, and thus make it impossible to secure. suflicient draft through the kiln. The spalls are therefore usually thrown away as refuse. To form a ,superionquality of lime from the waste materlal represented by the spalls, there is, according to the invention, a series of vertical passages 24,'disposed about the.

central shaft 10. The material placed in T these passages is thus caused to lie in contact with the wall of the central shaft 10, which walls are heated to a high temperature by the heat supplied to the material within the shaft. The heat which would therefore be ordinarily wasted is transferredto the 'spalls and they are changed to lime without contact with products of combustion or other foreign matter. To enable the resultant lime to-be drawn off from the passages 24 their lower ends are deflected, as at 25, .to openings into the passages 21, 22, suitable closures v26 being pro.- vided to control the discharge of material, which material may be received directly into the carts in the same manner as that from the central shaft 10. To facilitate the feeding of material to the 1 passages 24, hoppers 27 are shown at their upper ends. A protective skirting 28 is desirably placed about the material receiving opening of the shaft 10 to prevent abrasion of 'the walls of the shaft when material is discharged thereinto.

The kiln may be operate fully burned lime may bewit-hdrawn from the lower end of the shaft 10 or from the passages 24, and'newstone may be supplied at the top, as the material therein sinks downwardly, in the well known manner. Minor changes may be made in the physi-' cal embodiment of the invention without depapting from its spirit. f i

I claim:

1. A lime kiln comprising, in combi .a stack having a central passage to receive large pieces ofv lime stone, and a separate passage to receive smaller pieces of lime stone, a furnace to deliver products of combustion directly solely to said central pasd continuously,

natipn,

central passage as to have its contentsheated byconduction through a wall of the stack,

a separate closure at the bottom of each of passages whereby to retain material to said be treated therein and to permitfinished 'products to be selectively Withdrawn there:

from. i

2. A lime kiln comprising, in combination, a stack' having a central shaft, furnaces to deliver heated products of combustiondirectof the stack, a separate closure 1 solely to the interior of said shaft to directly heat large pieces of lime stone placed therein, a series of smaller passages surrounding said shaft and formed in the Walls of the stack adapted to have their contents heated by conduction through the Walls material by at the bottom of each of said-passages whereby to retain material to be treated therein and to permit finished products to be selectively withdrawn therefrom.

3. The process of burning lime which comprises placing relatively coarssfiroken lime forming material in achamber, eating said passing heated products of combustion through said chamber in contact with said material, placing relatively fine broken lime forming material in a chamber inthe Wall of said first named chamber and heating said fine tion of-heat through said Wall and entirely out of contact with products of combustion, whereby said fine material is changed to lime uncontaminated by products of combustion.

' WILBU RT WARD.

material solely by conduc- 

